TRENDS AND DETERMINANTS OF BLOOD PRESSURE IN AUCKLAND, NEW ZEALAND 1982-94

AIM: To describe blood pressure trends in Auckland, New Zealand from 1982 to 1994 and assess possible explanations for the trends. METHODS: Three cross sectional surveys of cardiovascular risk factors were undertaken in 1982, 1986-8 and 1993-4, with a total of 3806 European men and women aged 35-64 years randomly selected from Auckland electoral rolls. RESULTS: Mean systolic blood pressure fell in males from 132.2 mmHg in 1982 to 126.3 mmHg in 1993-4, and in females from 125.9 mmHg in 1982 to 121.7 mmHg in 1993-4. Both male and female diastolic mean blood pressure decreased more than 6 mmHg over the 12 years. The prevalence of antihypertensive drug use fell over the 12 year period. Regression analysis revealed a positive association between blood pressure and blood lipids. Body mass index (BMI) was also positively related to blood pressure while cigarette smoking was inversely related. However, concurrent trends in blood lipids, BMI and cigarette smoking could account for less than 6% of the average decline in systolic blood pressure over the 12 year period. CONCLUSION: There has been a substantial fall in mean blood pressure levels in Auckland adults aged 35-64 years which appears to be due to a shift in the general population blood pressure. The reduction in blood pressure is not explained by changes in pharmaceutical interventions and only a small part of the decline can be explained by concurrent trends in cardiovascular risk factors.